Catch Calculator incorrect?

If the calculator uses this formula:

Probability=1−( 1 −(BCR / (2∗CPM) ) )^Multipliers

And we assume no multipliers, straight ball pokeball toss AKA goplus on a Magikarp (BCR 70%)

For level 8 it should be ~93%
For level 15 it should be ~68%

The calculator says its 88% and 65% respectively. Is the calculator broken?